Belt conveyance device and image forming apparatus

Abstract

A belt conveyance device has a configuration where one end of a rotation shaft of an inclinable steering roller that can move an endless belt in the width direction is supported by a first support member that is pivotable on a first pivot axis extending in a first axial line direction intersecting the rotation axis of the steering roller, and the other end of the rotation shaft of the steering roller is supported by a second support member that is pivotable on a second pivot axis that is generally parallel with the rotation axis of another suspending roller and also extends in a direction generally orthogonal to the first axial line.

The invention claimed is: 
     
       1. A belt conveyance device, comprising:
 an endless belt; 
 a supporting roller configured to support the belt; 
 a steering roller configured to support the belt and configured to be inclinable with respect to the supporting roller to move the belt in a width direction; 
 a frame configured to rotatably support the supporting roller, the frame including a first side frame that rotatably supports a first end portion of the supporting roller and a second side frame that rotatably supports a second end portion of the supporting roller; 
 a first support portion configured to rotatably support a first end portion of the steering roller, the first support portion being rotatable about a first axial line substantially parallel to a rotational axis line of the supporting roller; 
 a second support portion configured to rotatably support a second end portion of the steering roller; 
 a detecting unit configured to detect a position of the belt in the width direction; 
 a steering drive unit configured to move the first support portion; 
 a controller configured to control the steering drive unit on the basis of a detection result of the detecting unit; 
 a pivot shaft attached to either one of the second support portion and the second side frame and rotatably supported around a second axial line intersecting with a rotational axis line of the steering roller; and 
 a bearing attached to the other one of the second support portion and the second side frame and rotatably supporting the pivot shaft. 
 
     
     
       2. The belt conveyance device according to  claim 1 , wherein the second axial line and the rotational axis line of the steering roller are substantially orthogonal. 
     
     
       3. The belt conveyance device according to  claim 1 , wherein, when the steering roller is substantially parallel to the supporting roller, the second axial line is substantially parallel to a line segment connecting a rotational center of the steering roller and a rotational center of a first support portion. 
     
     
       4. The belt conveyance device according to  claim 1 , wherein the second axial line passes through the steering roller. 
     
     
       5. The belt conveyance device according to  claim 1 , wherein the first axial line passes through the second axial line. 
     
     
       6. The belt conveyance device according to  claim 1 , wherein, when the rotation axis of the steering roller and the rotation axis of the supporting roller are substantially parallel, a straight line, which is substantially orthogonal to the first axial line and the rotation axis of the steering roller, is substantially parallel to the second axial line. 
     
     
       7. The belt conveyance device according to  claim 1 , further comprising an adjustment mechanism for adjusting a position of the pivot shaft or the bearing,
 wherein the adjustment mechanism adjusts the pivot shaft or the bearing so as to rotate around a third axial line parallel to the first axial line. 
 
     
     
       8. The belt conveyance device according to  claim 7 , wherein the pivot shaft is attached to the second support portion and the bearing is attached to the second side frame, and the adjustment mechanism adjusts the position of the bearing. 
     
     
       9. The belt conveyance device according to  claim 8 , wherein the third axial line passes through the second axial line and is substantially orthogonal to the second axial line. 
     
     
       10. The belt conveyance device according to  claim 9 , wherein the third axial line and the first axial line are substantially the same axial line. 
     
     
       11. The belt conveyance device according to  claim 1 , wherein the frame is a first frame, and the belt conveyance device further comprises:
 a drive source that rotationally drives the steering roller; and 
 a second frame being movable with the steering roller including:
 the second support portion, 
 a third support portion configured to rotatably support the one end portion of the steering roller, and 
 a connecting portion configured to connect the second support portion and the third support portion, 
 
 wherein the driving source is attached to the second frame. 
 
     
     
       12. The belt conveyance device according to  claim 1 , wherein the steering drive unit is attached to the frame. 
     
     
       13. An image forming apparatus, comprising:
 a belt conveyance device having an endless belt; and 
 a toner image forming unit configured to form a toner image on the belt, 
 wherein the belt conveyance device includes: 
 a supporting roller configured to support the belt; 
 a steering roller configured to support the belt and configured to be inclinable with respect to the supporting roller to move the belt in a width direction; 
 a frame configured to rotatably support the supporting roller, the frame including a first side frame that rotatably supports a first end portion of the supporting roller and a second side frame that rotatably supports a second end portion of the supporting roller; 
 a first support portion configured to rotatably support a first end portion of the steering roller, the first support portion being rotatable about a first axial line substantially parallel to a rotational axis line of the supporting roller; 
 a second support portion configured to rotatably support a second end portion of the steering roller; 
 a detecting unit configured to detect a position of the belt in the width direction; 
 a steering drive unit configured to move the first support portion; 
 a controller configured to control the steering drive unit on the basis of a detection result of the detecting unit; 
 a pivot shaft attached to either one of the second support portion and the second side frame and rotatably supported around a second axial line intersecting with a rotational axis line of the steering roller; and 
 a bearing attached to the other one of the second support portion and the second side frame and rotatably supporting the pivot shaft.